Fuel injection system for aircraft engines



Nov. 12, 1935. A. v. D. WILLGOOS ET'AL ,0

FUEL INJECTION SYSTEM FOR AIRCRAFT ENGINES Filed May 51, 1930 s Sheets-Sheet 1 INVENTOR also. am! Wis; .fl i /cw ouc I g I ATTOR Er Nov. 12, 1935. A. v. D. WILLGOOS El AL ,7

FUEL INJECTION SYSTEM FOR AIRCRAFT ENGINES Filed May 51, 1930 3 Sheets-Sheet 2 1510 as KTTORNEY Nov. 12, 1935. A. v. D. WILLGOOS ET AL 2,020,753

FUEL INJECTION SYSTEM FOR AIRCRAFT ENGINES.

Filed May 31, 1930 3 Sheets-Sheet 3 .III

Patented Nov. 12, 1935 UNITED STATE PA'E'EN OFFICE FUEL INJECTION SYSTEM FOR AIRCRAFT ENGINES Application May 31, 1930, Serial No. 458,798

15 Claims.

This invention relates to a fuel injection system for internal combustion engines and in particular to mechanism for injecting liquid fuel under pressure into an aircraft engine of the radial type.

More particularly the invention relates to an improved injection system for aircraft engines of the multi-cylinder radial type adapted to periodically admit liquid fuel unmixed with air into combustion chambers of an engine of the internal combustion type.

An object of the present invention is to provide improved hammer operated impact means for injecting liquid fuel directly to injection nozzles within cylinders of an internal combustion engine in predetermined order, the operating means therefor being driven by the engine but in a manner so that it is independent of the speed of the engine. g

Another object of the invention is to provide a hammer or impact member independently mounted relative to the plunger of a fuel injection jump and acting in alignment therewith, the hammer having spring means normally foreing it in a direction to force the pump plunger upon its discharge stroke, and being provided with cam .means acting directly upon the hammer member to move the plunger upon its suction stroke.

A further object of the invention is to provide means for controlling the extent of movement of the hammer member after first striking the pump plunger so that the amount of fuel admitted to a cylinder-at each stroke or blow of the hammer 35. upon a plunger may be regulated accurately and over a wide range.

A feature which enables the above objects of the invention to be accomplished is that the actuating mechanism for the hammer members 40 of the injection pumps is operated by means of and simultaneously with the suction and ,exhaust valve operating mechanism of the engine.

A still further object of the invention is to provide means for driving the actuating mem- 45 her for the hammer members in one direction only and permitting reverse operation of the engine, as in case of back-firing, without correspondingly reversely rotating the actuating members.

50 And finally it is an object of the invention to provide a connection between a pump plunger and its hammer member permitting limited relative axial movement, also enabling the movement of the hammer member in a direction 55 away from its plunger to force the plunger to move in the same direction therewith, resilient means being provided between the hammer and plunger and normally holding the hammer and pump plunger slightly spaced apart.

With these and other objects in view, our in- 5 vention includes the features of construction and operation set forth in the following specification and illustrated in the accompanying drawings.

In the accompanying drawings annexed here- 10 to and forming a part of this specification, we have shown our invention embodied in a preferred fuel injection system adapted primarily for a multi-cylinder engine of the radial type, but it will be understood that the invention can 15 be otherwise. embodied and that the drawings are not to be construed as defining or limiting the scope of the invention, the claims appended to this specification being relied upon for that. purpose. 20

In the drawings:

Figure 1 is a vertical sectional view taken longitudinally through the center line of a radial type aircraft engine showing the fuel injecting mechanism for one cylinder. 25

Fig. 2 is a cross sectional view of the mechanism shown in Fig. 1 taken upon the line 2-2 of Fig. 1 and showing the actuating mechanism for the hammers.

Fig. 3 is a view similar to Fig. 2 taken upon 30 the line 3-3 of Fig. 1 and showing the regulating mechanism for the stroke of the hammer members.

Fig. 4 is a perspective view of the actuating and regulating mechanism for one fuel injection pump, parts being broken away to more clearly show their construction, and

Fig. 5 is a detached perspective view of a pump plunger operating hammer or impact member.

In the above mentioned drawings we have 40 shown but. one embodiment of the invention which is now deemed preferable, but it is to be understood that changes and modifications may be made within the scope of the appended claims without departing from the spirit of the invention.

In the operation of internal combustion engines in which liquid fuel is injected directly into a cylinder and vaporized at that point, diflicultly has been encountered in obtaining perfect vaporization under low speeds and light loads. Under light loads the quantity of liquid being admitted for each explosive or power stroke is greatly reduced. Additional difllculties are encountered when the speed of the engine is so reduced that the speed ofgthe plungers in the pump or pumps forcing the liquid through the injection nozzle is greatly reduced in speed. The effect of the pump when operating slowly or when delivering reduced amounts of the liquid fuel is to cause the fuel to enter the injectionnozzle in such small quantity and atsuoh'a reduced velocity that vaporization is not complete resulting in greatly reduced eficiency, development of carbon deposits within the combustion chambers, and formation of dense exhaust gases.

The present invention primarily relates to a system of fuel injection for high speed high duty aircraft engines avoiding the above objections and operating to give substantially the same velocity of liquid fuel through the injection nozzles or other vaporizing means regardless of the speed of the engine or quantity of liquid injected, vaporization being equally complete in eaclrcombustion chamber under the lightest loads and slowest speeds of the engine. The fuel injection system illustrated in the accompanying drawings shows anapplication of such a system to an aircraft engine of the radial type operating upon a four-cycle system. More specifically the invention comprises improvements in the system. of fuel injection for internal combustion engines described and claimed in the patent to Hasbrouck 1,418,566 granted June 6, 1922.

Briefly and in its broadest aspect, the invention includes individual pumps having cylinderspreferably radially disposed, one pump being provided for each cylinder of the engine, each engine cylinder also having its own injection nozzle or vaporizing means and an individual fuel supply line from its pump cylinder. Each pump has a plunger of standard or usual type provided with multiple packing means along its stem permit-' this movement. V'i/ 'hen the cam operating a hammer to force a plunger upon its suction stroke releases a hammer the springs above referred to force the hammer suddenly and with considerable impact in a direction to strike against and move its pump plunger in the direction of its discharge stroke.

To enhance the impact effect or blow of the hammer upon its plunger, the connection between the hammer and .plunger permits limited relative axial movement, a small plunger disposed between these members and forced outwardly by a light spring normally .holding them slightly spaced apart. Movement of the hammer for a short distance therefore takes place before striking the end of the pump plunger. The amount of movement imparted to the plunger by a hammer, and therefore the amount of fuel delivered at each movement of a hammer and plunger outwardly, is regulated by interposing a stop limiting the outward movement of the hammer under the influence of the springs. This stop is preferably in the form of a spiral surface on a cam so that adjustment of the cam will vary the point the inner end of in the stroke of the hammer at which its movement is stopped. The cam means both for retracting the hammers and for regulating the amount of their outward movement are adapted I to simultaneously control all of the hammers. 5-

The cam for-retracting the hammers acts upon the hammers seriatim, and in a predetermined order, the regulating cam limiting outward movement of the hammers uniformly controls the hammers so that with any setting of the cams 10 eachpump delivers equal quantities of fuel -to its injection nozzle. i

Referring more in detail to theflgures of the drawings, a front frame member ll! of an aircraft engine is shown in section within which is 13 rotatably mounted the main'crank shaft I I. This shaft II is preferably mounted upon anti-friction bearings l2, one only of which is shown in Fig. 1.

The engine shown fragmentarily in the drawings 7 is-of the multi-cylinder radial type internal com- 20 bustion engine, one of the cylinders I3 being partly shown in Fig. 1. The engine is equipped with a usual or standard form of multiple cam 14 for actuating the suction and exhaust valves (not shown). The valve operating rod l5 for 25 one valve is shown in Fig. 1. This cam I4 is suitably and rigidly supported upon a disc i6 freely rotatable upon a sleeve l1 surrounding the main crank shaft II. This valve operating cam I4 is also adapted, as usual, to be driven by a; 30

gear'l8 suitably secured to the main crank shaft II. This gear l8 drives an intermediate compound gear I 9 supported within engine frame member ID, the pinion member of which meshes with internal teeth 20 provided upon the cam 3.;

l4. Contacting with the periphery of cam are valve rods: I5 (only one being shown) enclosed within a tube 2|, a tappet 22 being provided with v the usual form of roller or follower for engagement with the peripheral cam surface. inner ends of the tubes 2i enclosing the tappets 22 are mounted in fixed position in and extend through an annular member 23 securely fastened to the forward surface of the engine frame member l0. 45

are those usually found in engines of the type illustrated but may The above mentioned parts be, widely varied from the particular construction shown. No further description of these parts is therefore thought to be necessary. 5

- Secured concentrically with the main crank shaft II and fastened to the annular member 23 supporting the valve actuating rods I5 is a pump body member or carrier 25. This member 25, as

shown, is secured at its periphery to the member 5 23 and houses an anti-friction bearing 26 sup-, porting the forward end of the main crank shaft ll. 2

Secured at the periphery of the carrier 25 are the body members containing the cylinders of so fuel pumps 21, these, as shown, being secured substantially radially upon the carrier" and hav ing intake and discharge valves 28 and 29 respectively as shown in Fig. 1. A pump plunger 30 operates radially within a. carefully formed 5 cylinder extending radially within each pump 21, which is provided with a head 3| interlocking loosely with a flanged portion upon the outer end of its actuating hammer 32. Within this body member or carrier 25 areradial- 70 ly arranged slots or openings, one slot being provided for each of the engine cylinders. Within The 40 v Liquid fuel may be supplied to the cylinders 21 from a circular manifold 33 constantly maintained filled from any suitable source of supply. From this manifold 33 branch pipes 34 extend to each cylinder 21, a suitable connection being provided from each branch 34 to its member 35 which is preferably threaded into its cylinder 21 and within which is mounted one of the suction valves 28. Similarly disposed upon the opposite side of the cylinder 21 is a member 36 housing one of the discharge valves 29 and within which is connected a supply pipe 31 leading to a suitable injection nozzle or vaporizing means (not shown) within one of the engine cylinders i3.

From the above described means it will be seen that movement radially of a hammer 32 in opposite directions will correspondingly move its pump plunger 30 in the same direction and force liquid from the pump cylinder 21 through intake valve 28 and through the discharge valve 29 into supply pipe or conduit 31 leading to a nozzle or vaporizer (not shown) in cylinder I3. Movement of the hammer 32 inward draws the liquid into the pump cylinder 21 through valve 28 and outward movement discharges it through the valve 29 from the pump to the supply line 31. It will be noted that the hammer 32 and pump plunger 39 in the position shown are held slightly separated, this being accomplished by means of a lightly pressed plunger 39 housed within the inner end of the pump plunger 30 and bearing against the outer end face of the hammer 32. This plunger 39 is pressedby its spring with suflicient pressure normally to hold the pump plunger 39 and hammer 32 slightly separated, as shown, so that, at the beginning of the outward radial movement of the hammer 32, the hammer must move a short distance and acquire a certain amount of momentum before striking and moving its pump plunger 30.

Normally forcing the hammer 32 outwardly in the direction of the discharge stroke of the plunger 30 are springs 4|], two of which are shown, these being conveniently housed within a recessed portion of the hammer and extending axially thereof. The inner ends of these springs 49 bear against a supporting member 4| fitting within a suitable cylindrical opening in the carrier 25. The outer ends of the springs 40 bear directly upon a transverse surface adjacent the upper end of the hammer 32. The compression of the springs 40 normally operates to strongly force the hammer 32 in an outward direction to move its pump plunger 30 in the direction of its discharge stroke.

To move a hammer 32 inwardly against the force of its springs 40 to eifect'the suction stroke of the plunger 30, a cam 42 is provided contacting'with the outer surface of a lateral projection- 43 outstanding from the hammer 32 near its inner end. The cam 42 may be and preferably is of annular form, the engaging surfacesof which are on its internal surface and in the form of spirals. This cam member 42 may be secured within a laterally projecting annulus on a member 44 rotatably mounted on a portion of the member 4| within which the anti-friction bearing 26 is mounted. This cam 42 is, as shown most clearly in Fig. 2, provided with four radial surfaces or walls 45 and four spiral surfaces 46-so that as the cam 42. is rotated in the direction of the arrow shdwn in Fig. 2 the hammers 32 are successively forced inwardly by engagement of the projection 43 with one of the spiral surfaces 46. When the cam 42 reaches a position where a spiral surface 46 runs off the hammer projecand consequently the pumps 21 will operate to tion 43 and one of the radial surfaces 45 on the cam passes the side wall of the projection 43, the hammer is released for outward radial movement. The springs 40 compressed during the inward movement of the hammer 32 thereupon expand and force the hammer suddenly outwardly.

To rotate the hammer operating cam 42 and the member 44 on which it is mounted, the disc l6 carrying the valve operating cam I4 is provided with a ring 41 having four notches 48 cut within an inner annular surface. This member or ring 4'! is most clearly shown in Fig. 2. Engaging in one of these notches 48 is a pawl or detent 49 supported on the member 44 carrying the cam 42 and normally spring-pressed outwardly into its engaging position. If desired, two of these pawls or detents 49 may be employed diametrically disposed on the member 44. Rota. ion of the disc l6 and the ring 41 will therefore force the, disc member 44 and the hammer actuating cam 42'thereon to rotate in the same direction and speed as ihe valve operating cam l4. The form of notch 48 and pawl or detent 49 are such that when rotating in the normal direction a radial surface on the notch 48 engages a substantially .radial surface on the pawl or detent 49. In the event of back-firing of the engine or other cause and consequent reverse rotation of the crank shaft ll and cam l4, rotation of the hammer actuating cam 42 would not occur "but would merely cause the pawl 49 to ratchet over relative to the ring member 41 against the pressure of its spring. Rotation again of the crank shaft I l and parts operated thereby in the proper direction causes the pawl or pawls 49 to engage one of the notches 48 within the ring 41. This engagement of the pawls 49 will properly reposition the cam 42 relative to the other parts of the engine for operation. The cam 42 will be roated inject fuel into the cylinders l3 at the proper instant so long as the'crank shaft H is rotating in the proper direction. As the cam 42 is rotated at the same speed as the valve operating cam l4 the fuel injection will always be operated in proper timed relation to the operation of the valves.

To regulate the amount of liquid fuel forced by a stroke of a plunger, cam means areprovi'ded to limit the outward movement of the hammers 32 when released. For this purpose a second projection 50 is provided outstanding laterally from the hammers upon the same side as the projection 43 referred to above. This projection 50 is adapted to be engaged by one of the spiral surfaces 5| on a cam 52 most clearly shown in Fig. 3. By varying the rotative position of this cam 52, which has angularly spaced spiral surfaces 5| upon an internal surface equal in number to the number of hammers 32 to be regulated, the outward movements of the hammers 32 are uniform-- 1y stoppedafter any predetermined and adjustable 'stroke of the hammers 32. Consequently outward movement of the plungers 30 is correspondingly stopped.

As the camsurfaces 5| directly engage the projections 50 on the hammers 32 further movement of the hammer is instantly stopped. As the cam surfaces may be so formed that slight variations of movement of the hammers may be accomplished the regulation of the movement of the pump plungers 39 may be accurately regulated. In addition no part of the pump plungers 30 has to absorb the momentum of the hammer blow occasioned by the I hammer being suddenly i stopped. Theplungers .are thus freed from the strains occasioned by the sudden stopping of the hammers.

. The cam 52 is preferably rotatably adjustable within a retaining member 53 rigidly secured to an inner face of the carrier 25, this member also serving to enclose the hammers 32. To effect rotative adjustment of this regulating cam 52 to vary the stroke of the hammers 32 the cam is provided upon its outer. surface with a number of gear teeth 54 adapted to be engaged by teeth of a spur gear 55. This spur gear 55 is secured upon the inner end of a shaft 56 extending.-

through the carrier 25 and having a crank 51 keyed to its outer end, Oscillation of this crank 51, as by means of a reach rod 58, variesthe angular or rotative position of the 'cam 52 and for internal combustion engines comprising in combination, a pump, a plunger therefor, a hamtherefore the extent of outward movement permitted thehammers 32. Each of the spiral surfaces 5| corresponds to and is equally spaced from the others so that rotary adjustment of the cam 52 simultaneously and equally affects each .of the hammer movements. The quantity of fuel A delivered from each pump 21 byach discharge stroke of the hammers 32, with the cam 52 in ,any adjusted position, is therefore uniformly varied over the complete range of adjustment.

What we claim is: i l. Actuating means for a fuel injection system for internal combustion engines comprising in combination, a pump, a plunger therefor, a hammer interconnected with said plunger and normally held slightly spaced therefrom, cam means to move said hammer and plunger in one direction, and resilient means to force said hammer .1 in the opposite direction.

2. Actuating means for a fuel injection system,

for internal combustion engines comprising in combination, a pump, a plunger therefor, a hammer interconnected with said plunger and normally held slightly spaced therefrom, cam means engaging said hammer to move said hammer and plunger in one direction, and resilient means compressed by operation of said cam. means to force said hammer in the opposite direction.

3. Actuating means for a fuel injection system hammer in oppositerdirections will correspond-.

ingly move said plunger, means resiliently foreing said hammer and plunger slightly apart, cam means to move said hammer in one direction, and resilient means to move said hammer in the opposite direction.

5. Actuating. means for a fuel injection system -for internal combustion engines comprising in combination, a pump, a plunger therefor, a hammer loosely interconnected thereto so that movement of said hammer will actuate said plunger, cam means to ,move said hammer and plunger in one direction, and spring means to force the hammer in the opposite direction.

6. Actuating means for a fuel injection system for internal combustion engines comprising in combination, a pump, a plunger thereforpa hammer loosely interconnected thereto so that movefor multi-cylinder' tion to effect the discharge-strokes-of said plungment of said hammer in opposite. directions will actuate said plunger in opposite directions, means engaging said hammer for moving said hammer and plunger in one direction, and resilient means engaging said hammer acting on said hammer for 6 forcing said hammer and plunger in the opposite direction.

7. Actuating means for a fuel injection system for internal combustion engines comprising in combination, a pump, a'plunger-therefor, a ham- 10 mer loosely interconnected thereto for limited axial movement and so that movement of said hammer will actuate said plunger, means driven by said engine to move said hammer in a direction to effect movementof said plunger upon its suction stroke, and resilient means to force the hammer and plunger in the opposite direction. 1

8. Actuating means for a fuel injection system internal combustion 'engines comprising in combination, a plurality of pumps radially disposed and corresponding in number to the number of engine cylinders, plungers for said. pumps movable radially of said engine, hammers loosely connected to said plungers and normally spaced therefrom for movement in alignment with said plungers, cam means driven by said engine to individually move said hammers inwardly, and spring means compressed by inward radial movement of said hammeis for forcing said hammers radially outwardly against said plungers when released from said cam means.

9. Actuating means for a fuel injection system for multi-cylinder internal combustion engines comprising in combination, a plurality of pumps 35.

radially disposed, each pump having a. discharge conduit to an engine cylinder, plungers for said pumps movable radially of said engine, hammers loosely connected to said plungers for limited axial movement relative thereto, cam means to 40) individually move said hammers inwardly, individual resilient means for each hammer to force said hammers against their plungers, and cen- 'trally disposed rotatable means for adjustably limitingthe outward movement of said hammers.

10. Actuating means for a fuel injection system for multi-cylinder internal combustion en-' gines comprising in combination, a plurality of pumps radially disposedfeach pump having a discharge conduit to an engine cylinder, plungers for said pumps movable radially of said engine,

Y hammers loosely connected tosaid. plungers;

means engaging said hammers to individually move said hammers and plungers inwardly, resilient means for eachhammer to force said hammers against their plungers, and means en'- gaging said hammers to uniformly adjust the amount of movement of said hammers in a direcers. 11. Actuating means for a fuel injection pump for internal combustion engines comprising in combination, a cylinder, a plunger operating therein, a hammer connected to said plunger in alignment therewith and permitting limited axial movement therewith, resilient means normally forcing said hammer and plunger apart, and means to actuate said hammer to operate said plunger.

12. Actuating means for a fuel injection pump for internal combustion engines comprising in combination, a cylinder, a plunger ,operating therein, a hammer slidably mounted for movement in alignment with said plunger, an inter-'- locking connection between. said hammer and plunger permitting relative axial movement of said hammer and plunger, actuating means for said plunger engaging said hammer for moving said hammer and plunger in one direction, and resilient means forcing said hammerin a direction opposite that in which it is moved by said actuating means, said resilient means being free to act when said hammer reaches the end of its movement eiiected by said actuating means.

13. Actuating means for a fuel injection pump for internal combustion engines comprising in combination, a plurality of radially disposed cylinders, plungers operating therein, hammers slidably mounted for individual movement in alignment respectively with said plungers, an interlocking connection between each of said hammers and its plunger permitting limited relative axial movement therebetween, centrally mounted actuating means successively engaging said hammers for moving said hammers and their plungers in one direction, and resilient means normally forcing a hammer and. its plunger apart from each other.

14. Actuating means for a fuel injection system for multi-cylinder internal combustion engines comprising in combination, a plurality of radially disposed pumps, pump plungers therein, individual means connected to said plungers for effecting operation thereof, a centrally mounted rotary member for actuating said means to effect the suction movement of said plungers, resilient means to effect the discharge movement of said plungers when released by their actuating means,

a ratchet on said rotary member, a ratchet wheel mounted concentrically with said rotary member and engaging said ratchet for rotating said centrally mounted member in one direction to operate said plungers in proper timed relation in 5 the cycle of operation, of the engine but preventing rotation thereof in the opposite direction, and

a centrally disposed rotatable member for limiting the discharge movement of said plungers.

15. Actuating means for a fuel injection-sys- 1o tem for multi-cylinder internal combustion engines comprising in combination, a cylinder frame member, a main shaft supported therein, a plurality of pumps radially arranged and disposed concentric with said main shaft, pump plungers 15 within said pumps, means connected to said plungers and engaging an actuating member to efiect the suction movement thereof, resilient means to eifect the discharge movement of said plungers when said connected means are released 20 from said actuating member, a rotary member concentric with said main'shaft engaging said actuating member and operated by said main shaft to rotate said actuating member, a one-way driving connection between said rotary member 25 and said actuating member whereby said actuating member and shaft are maintained in proper rotative relation for driving said member in one direction only, and a rotary member concentric with said main shaft for limiting the discharge a0 movement of said plungers.

- a ANDREW V. D. WILLGOOS.

STEPHEN A. HASBROUCK 

